Notes

All living things are composed of cells. They are the building blocks of all life. Cells come in many different shapes and have different functions. Plant and animal cells are different too. The main difference between plant and animal cells is that plant cells have a cell wall on the outer layer, whereas animal cells only have a cell membrane

All living cells and many of the tiny organelles internal to cells are bounded by thin membranes. These membranes are composed primarily of phospholipids and proteins and are typically described as phospholipid bi-layers

All living organisms on Earth are divided into cells. The main concept of cell theory is that cells are the basic structural unit for all organisms. Cells are small compartments that hold the biological equipment necessary to keep an organism alive and successful. Living things may be single-celled or they may be very complex such as a human being.